It has long been known that fatty substances could be cooled to a solid or semi-solid by applying a hot or warm liquid or semi-liquid of the fat to a rotating drum or continuous cooling belt. In U.S. Pat. No. 788,446 to A. R. Wilson, a liquid fat is sprayed onto a rotating drum or cylinder which is cooled with ice or ice and salt. As the drum rotates, the previously applied liquid is scraped from the drum, and the scraped area of the drum is then subsequently presented for another application of the fat or liquid to be congealed.
These types of drum cooling or mechanical cooling are relatively successful for substances having a sufficiently high melting point. However, as the melting point decreases, the resident's time of the substance on the drum must be increased in order to chill the liquid to a sufficient hardness that upon scraping the substance from the drum, the material cleanly breaks free of the drum and is sufficiently solid that it does not melt together with other materials scraped from the drum. In addition, as the melting point of the liquid applied to the drum becomes lower and lower, the opportunity for the material to melt together again, or to agglomerate, increases due to the continued release of heat from within the formerly liquid substance as it becomes more and more solid after being scraped from the roller and packaged.
In particular, as a substance is chilled to change the material from a liquid to a solid, the heat within the liquid substance is removed, and the material is reduced in temperature to a point at which crystallization of the material begins and a solid of the material begins to form within the liquid. The solid formation increases as heat is removed from the liquid substance. After a time, sufficient heat will have been removed from the substance so that the once liquid material becomes generally solid. However, while a material has become generally solid, it may not be fully crystalized and stabilized at a useful temperature. Rather, the material will continue to undergo greater solidification as an increasing percentage of the material becomes a solid crystal. During this period of continued crystallization, heat continues to be given off by the material as it turns from a semi-solid into a solid or becomes stabilized at a particular temperature below the melting point of the original liquid substance. This represents the release of the “heat of crystallization” or the release of the “latent heat of crystallization” of the substance.
In the process of forming chips or flakes from triglycerides, emulsifiers or other edible and non-edible materials, the general process is to apply the liquid substance to a rotating, chilled drum, and to allow the material to stay in contact with the drum for sufficient time to permit the liquid to become sufficiently solid that it can be scraped from the drum. During the scraping process, it is preferred that the solid or semi-solid break into flakes or fragments rather than peeling from the drum as a continuous sheet. Once the flakes or fragments of the substance are removed from the drum, they are usually packed into a container and placed into a cooling room for additional cooling and to retain the material in a solid state. It is during this period in the cooling room that additional solidification of this substance continues. As a result of this further solidification, internal heat is given off by the material which is referred to as the “latent heat of crystallization.” Once crystal growth, or solidification, has been initiated in a substance, it is necessary, for additional solidification to occur, that heat be removed or transferred from the body undergoing crystallization or solidification. In the case of a partially solidified liquid which has been placed into a packing box, the latent heat of crystallization becomes trapped within the mass of material in the box and begins to generally raise the temperature of the substance. This can result in the material within the package agglomerating due to the latent heat of crystallization partially melting the solid which was formed on the rotating cold drum.
A graphical representation of this phenomenon can be seen in FIG. 6. In FIG. 6, the intermittent line indicates material having a melting point of approximately 114° F. which was initially cooled for 10-30 seconds on a roller. The graph shows that during the mechanical cooling period (T1) the temperature decreases from generally 5° F. above the melting point temperature of the fat to be flaked to approximately 50° F.-60° F. At time T2, packaging occurs as the material is scraped off the roller. At time T2, the time interval changes to days. Once the material is removed from the roller the temperature of the material begins to rise. This rise in temperature continues during the first portion of time T2 and after the packaged material is placed into a 40° F. cooling room. It is shown in FIG. 6 that the temperature of the material once packaged and residing in a cooling room continues to rise. This temperature increase is due to the latent heat of crystallization which causes the temperature of the packaged material to increase to approximately 100° F. The temperature of the material then decreases to the temperature of the cooling room over a period of an additional two to three days. This increase in temperature in the packaged material resulting from the latent heat of crystallization can cause agglomeration of the packaged material.
This rise in latent heat is a particular problem in materials having a Solids Fat Index which is below the line graphed in FIG. 10. FIG. 10 shows the solids content of a mixture of fats at various temperatures. The solids fat index is a manufacturing standard used to measure the extent of hydrogenation in the fat components used in a mixture. Over a limited range, the solid fat index (SFI) value is numerically, approximately equal to the actual percent solids in the mixture. At high temperatures, the fat product will be completely melted. At low temperatures, the fat can be completely solid. In between these low and high temperature ranges, there are varying degrees of solid fat content in the fat composition. By selection of varying degrees of hydrogenated triglycerides, a variety of SFI profiles for various fat compositions can be developed. With respect to fat mixture suitable for flaking, the line in FIG. 10 represents an agglomeration boundary. For mixtures of hydrogenated triglycerides having solids compositions which fall below the agglomeration boundary, conventional drum and belt methods of flaking do not provide sufficient chilling time or sufficient temperature reduction in the mixture to: (1) produce sufficient nucleation in the fat mixture to allow flaking; (2) prevent the solidified fat from forming a sheet of material, rather than flaking; and (3) reduce the temperature of the solidified material sufficiently to avoid re-melting of the material due to the latent heat of crystallization once the material is removed from the belt or roller and packaged.
The present invention avoids all these problems of roller and belt flaking devices and permits the flaking of fat and/or emulsifier mixtures which have a solids content which is below the agglomeration boundary shown in FIG. 10.
Yet another drawback of the use of drum cooling for materials of the kind previously described is that when the melting point of the material becomes sufficiently low, generally 105° or below, the latent heat of crystallization will tend to be sufficient to virtually remelt the material or to cause the flakes or chips of the material to become a connected mass within the packaging material. Therefore, the use of rotating drum devices to cool materials having low melting points becomes ineffective, and triglycerides and other oils which have low melting points cannot be mixed with other substances which would have the effect of lowering the melting point of the triglyceride or the fatty substance to a point at which the drum cooling method would be ineffective as a result of the latent heat of crystallization causing the newly solidified material to form a mass once placed into packaging.
Another problem is commonly encountered with emulsifiers that do not contain a sufficient amount of nucleating hard fat to initiate crystallization. In this case the emulsifier does not form a flake or a chip when cooled, but forms a continuous sheet of material which peels off the belt or drum cooling device
It will be appreciated by those skilled in the art that increasing retention time on the cooled rotating drum is an insufficient solution to this problem. Depending on the material being applied to the drum, if it is cooled too completely while on the drum, it will crack away from the drum and fall off the drum prior to it reaching the scraper blade or reaching a point at which collection of the material is desired. In certain types of drum cooling systems, the liquid is applied by the bottom of the drum rotating through a vat or pool of warmed liquid. The liquid then adheres to the drum and is cooled during the rotation of the drum, and the material is scraped from the drum prior to a second emersion in the vat of liquid. In this situation, slowing the drum can result in substantial loss of heat into the vat of hot or warm oil or triglyceride and can result in the heating of the material in the vat and the cooling of the drum operating at cross purposes.
Therefore, it would be beneficial to the food industry in general if an apparatus and method were available to solidify low-melting triglycerides and edible oils, emulsifiers and mixtures thereof and the like which avoided the drawbacks of the cold drum method of forming such solids. In addition, it would be a great benefit to the food industry if the method and apparatus allowed multiple substances to be layered upon one another to form a sandwiched solid of several different materials which could then be chipped or flaked and incorporated into foodstuffs.
The aforementioned debilities are overcome by the present invention, and the desirable advantages and solutions of the present invention will become apparent to those skilled in the art upon reading the following specification in conjunction with the drawings provided herein of a preferred embodiment of the invention.